1. Field of the Invention
The field of invention relates to window frames, window sashes, and means to secure window sashes to window frames.
2. Description of the Prior Art
In order to set a glass in the opening of a wall panel, there is a generally known method for glazing by the steps of securing a window frame, often made of aluminum or steel, to the inner periphery of a wall panel opening and fitting and fixing the circumferential outermost edges of the glass into a glazing portion of the window frame. However, when using window frames made of aluminum or steel, there are problems of moisture condensation, in that dust mixes with the moisture to make the surrounding portion around the window glass dirty. Condensation also accelerates corrosion and rust, and the fireproofing and heat resisting properties of these prior art frames are comparatively inferior. Furthermore, there is a tendency to make these prior art window frames thinner to reduce weight, and thin, lightweight, window frames cause additional problems with respect to reduced waterproofing and thermal insulation. In addition, it is difficult to design a lightweight aluminum or steel window frame which appears to be solid and of high quality.